Use Jimp to convert a .jpg image to png in Node.js (AWS Lamda)

I'm writing an AWS Node.js Lambda function (using Serverless) to convert images across different formats (i.e. JPG--> PNG) given an initial URL. I'm using the Jimp library which, according to the documentation, implements this functionality with the code:

Jimp.read(JPG_URL, function (err, image) {
  if (err) {
    console.log(err)
  } else {
    image.write("new-image.png")
  }
})

now, in my Lambda function I'm using:

let img_data = await Jimp.read(JPG_URL);

which works well, indeed I can use img_data to perform different transformations (i.e. img_data.greyscale()). The problem is that (AFAIK) Lambda's filesystem is read-only and Jimp doesn't seem to support a way to convert directly to a variable.

How can I perform the conversion without relying on the filesystem?

You may try sharp like below

const sharp = require("sharp");

async function convert() {
  try {
    await sharp("myfile.jpeg").png({ palette: true }).toBuffer()
  } catch (error) {
    console.log(error);
  }
}